Multi-segment composite photocell device

Abstract

An improved photocell configuration is provided to create a more accurate laser receiver that not only is very accurate and flexible in its operational capabilities, but also can greatly reduce the effect of rotational offset due to shading of the photocell. In one embodiment, a very long photocell is provided in which multiple split-cells are used to present a geometry that will tend to negate some of the effects of shading. The shading effects are minimized by having a different active photocell area along each vertical edge of the photocell. In another embodiment, a 'segmented' photocell is used, in which the split-cell design of a long photocell is also divided into vertical segments. These segments can be re-configured so that alternating segments comprise a mirror image about the longitudinal of the long photocell. Such an arrangement tends to reduce the effect of rotational offset due to shading to an extremely small percentage of error. The segmented photocell configuration of the present invention is capable of being manufactured in 'cell units' of relatively small length that can be stacked up next to one another to build a very long photocell. Each of the smaller segmented photocell structures can be manufactured using standard integrated circuit processing in lengths of less than two inches for ease of manufacture.